. the middle class' most cherished tax break could be in the crosshairs of the fiscal cliff negotiations. we're talking about the mortgage interest deduction. it's been around for 99 years, but it's costing the government $80 billion this year and will reach $100 billion by 2014 making it the third largest tax expenditure according to the congressional research service. who is it really helping in the most recent irs tax data show 41 million people claim this deduction on their 2010 taxes, but the tax policy center points out it tends to benefit upper middle class families the most. for those with annual incomes of less than $40,000 a year, the average tax savings is just 91 bucks. for the people earning $250,000 a year, the annual tax savings runs about $5,500, and critics say it's not really helping to boost homeownership. going to talk to one of them in a moment. the homeownership rate in the u.s. is now about 65%. it was up near 70% during the housing boom in 2005 and 2006. now we're back to levels we last saw in the 1990s. yes, the great recession is partly to blame, but the fact is we'